Light emitting diode (LED) has been used in the fields of lighting, display and many others for many years. Due to its high efficiency of power saving and great lighting affect, the application of LED has been widely spread throughout the industry as such, the corresponding new technologies of how the LED is made, packaged and applied are introduced to the world over and over again in the past years. The related art like: U.S. Pat. No. 9,231,171 related to an LED module, U.S. Pat. No. 9,179,543 related to the making of via in the substrate; U.S. Pat. No. 7,752,792 discussing about how two LED modules are combined and U.S. Pat. No. 6,893,890 concerning about the wires formed on a substrate is constantly developed to promote the technology to march toward a more economic and convenient way of making an LED module. However, reviewing these patents gives people an impression that all those patents or currently commercially available technology focus on the thin-film technology (TFT) or printed circuit board method (PCB). As well known in the art that when the method of making something is related to TFT, the base cost is high and the processes involved are complicated, which builds a high-wall to people who are interested to join or have interest in developing new technology.
Another technology involving LED is the Active-Matrix Organic Light Emitting Diode (AMOLED). Basically, the technology used in AMOLED is pretty much related to TFT, and the differences therebetween is that an organic phosphorous powder is used to generated required light through the activation of current. As said earlier, this technology is very closely related to TFT, which also sets a high bar to the industry. Even so, in order to pursuit high resolution, a newly developed technology called micro-LED is surfaced to simplify the problems that the OLED industry is facing, involving, but not limited to, the obtaining of organic phosphorous material, the packaging technology used to package the glass once the OLED module is completed . . . etc. The implementation of micro LED may actually solve some of the problems that OLED faces, however, the alignment of transfer of millions of electronic devices to another support substrate may still need time to really commercialize the technology. Still, to further simplify the TFT process, another technology is currently under development, i.e., printed electronics.
The attraction of printing technology for the fabrication of electronics mainly results from the possibility of preparing stacks of micro-structured layers (TFT) in a much simpler and cost-effective way compared to conventional electronics. Also, the ability to implement new or improved functionalities plays a role. The selection of the printing method used is determined by requirements concerning printed layers, by the properties of printed materials as well as economic and technical considerations of the final printed products.
Inkjets are flexible and versatile, and can be set up with relatively low effort. However, inkjets offer lower throughput and lower resolution. It is well suited for low-viscosity, soluble materials like organic semiconductors. Because ink is deposited via droplets, thickness and dispersion homogeneity is reduced. Using many nozzles simultaneously and pre-structuring the substrate allows improvements in productivity and resolution, respectively. However, in the latter case non-printing methods must be employed for the actual patterning step.
Screen printing is appropriate for fabricating electrics and this method can produce conducting lines from inorganic materials (e.g. for circuit boards and antennas), but also insulating and passivating layers, whereby layer thickness is more important than high resolution. This versatile and comparatively simple method is used mainly for conductive and dielectric layers, such as the conductive lines for the touch-screen. However, it is quite a feature for printing the conductive lines for the use of, i.e., touch screen. Due to the consideration of transparency for touch screen, the material for the conductive lines is primarily ITO (90% of Indium, 10% Tin oxide). This is largely used in the transparent conductive layer in the TFT for LCDs (liquid crystal display) or the touch screen for mobile phones or touch counsel for laptop computers. Because of the consideration of induced current generated by the capacitors that are located on the matrix of conductive lines and of the consideration of transparency, the electric current required for touch panel and passing through the conductive lines have to be transparent to allow users to see through the cover glass and a width capable of bearing only a small amount of current.
Still, there is a technology used widely in the electrical appliance industry, i.e., printed circuit board (PCB). The conductive wires are first printed on a carrier (substrate), then via is defined through the carrier to electrically connect the conductive wires on opposite sides of the carrier. The conductive wires of PCB may be transparent or opaque depending on the requirements. This technology has been used for many years and is widely acknowledged by the skilled person in the art. The PCB process, though widely implemented in different fields, still faces problems that bother the manufacturers, the heat dissipation. As the electronic devices take relatively a large amount of space on the carrier compared to the conductive lines, the heat generated by the electronic device needs to be dissipated in order to maintain great efficiency of the electronic devices. Therefore, the device responsible for heat dissipation takes another portion of inner space inside the entire assembly.
It is an objective of the preferred embodiment of the present invention to provide a method for making an LED module that is easy to proceed and maintain the transparency of the carrier to allow users to see through the carrier when not activated.